Common Stock and Preferred Stock - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 1 Months Ended 12 Months Ended
Aug. 19, 2014
Jul. 30, 2014
Jun. 30, 2015
Aug. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Class of Stock [Line Items]              
Common stock, shares authorized         100,000,000 100,000,000  
Preferred stock, shares authorized         5,000,000 5,000,000  
Preferred stock, par value         $ 0.0001 $ 0.0001  
Voting right description         Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company's stockholders.    
2014 Stock Option Plan [Member]              
Class of Stock [Line Items]              
Common stock shares, reserved         3,777,695    
Common Stock [Member]              
Class of Stock [Line Items]              
Number of shares issued         3,200,000 5,750,000 100,378
Number of common shares issued on conversion of redeemable convertible preferred stock           12,440,205  
Common stock, shares authorized   100,000,000          
Preferred Stock [Member]              
Class of Stock [Line Items]              
Preferred stock, shares authorized   5,000,000          
Preferred stock, par value   $ 0.0001          
IPO [Member] | Common Stock [Member]              
Class of Stock [Line Items]              
Number of shares issued   5,000,000          
Common stock, price per share   $ 13.00          
Number of common shares issued on conversion of redeemable convertible preferred stock   12,440,205          
Proceeds from issuance of shares   $ 57,337          
Over-allotment Option [Member] | Common Stock [Member]              
Class of Stock [Line Items]              
Number of shares issued 750,000     750,000      
Common stock, price per share $ 13.00     $ 13.00      
Proceeds from issuance of shares $ 9,068     $ 9,068      
Follow-on Offering [Member] | Common Stock [Member]              
Class of Stock [Line Items]              
Number of shares issued     4,600,000        
Common stock, price per share     $ 22.00        
Proceeds from issuance of shares     $ 65,612        
Number of shares offered by company     3,200,000        
Number of shares offered by stockholders     1,400,000